Vibratable reed are used in such musical instruments as accordions, melodeons, concertinas, harmonicas, harmoniums, and melodicas.
The reed in such instruments usually consist of a strip of metal, or tine, fixed at one end, as in a cantilever, and its vibration in air produces a source frequence that is determined largely by the geometric and elastic properties of the reed. All surfaces of the reed, except the fixed end, are in contact only with air.
Thus, the vibration of the reed is "free." Other reeds, called "beating" reeds, contact immovable surfaces during vibration, periodically opening and closing a port. This creates resonance in an air column whose natural vibrational frequency largely determines the pitch of the resulting musical tone.
An example of beating reeds is found in some organ pipes consisting of metal, and the vibrations of both the air column in the pipe and the reed coicide for enhanced creation of a musical tone.
In music, pitch is a characteristic of a tone, or sound, that allows placement of the tone in an ordered musical scale with other tones. A tone is an element of sound determined by the frequency of vibration of sound waves reaching the air, so that the higher the freuency the higher the pitch.
Timbre is a characteristic of a tone that distinguishes the tone from other tones having the same pitch and loudness, and can be described, at least in part, by the relative magnitudes of overtones making up the tone.
In some free reed instruments, the flow of air is bi-directional, i.e. into and out of the instrument. In such cases, it is desirable for the resulting musical tone to have the same combination of pitch and timbre for both flow directions of flow.
A single, conventional reed cannot function with air flow in both directions. Because of the asymmetry of reed construction, with only one edge of a quiescent reed projecting above the surface of a reed plate, away from the reed slot, air flow can activate the reed from only one direction. It is thus necessary to construct such instruments with one set of conventional reeds for inflow, and another set for outflow. The larger reeds of these instruments usually contain one way valves, or leather flaps, that shut off air to the inactive reed and prevent air leakage. This occurs when the direction of air flow cannot support vibration in that reed. There is thus a duplication of reed construction in such instruments in conventional, single action reed design.
In addition, the need for leather flaps often can be troublesome. The flaps often hang up on nearby surfaces, cause changes in tuning as they age, and even cause changes in musical pitch when increased air flow bends the flaps further away from the reed slot.
The timbre of the musical tone produced by a vibrating free reed can depart from the pure tone of a sinusoidal vibration because of sudden, step-like air pulses against the reed as the pulses passes through the slot of the reed plate. Such pulses contain many overtones, which greatly affect timbre. The conventional free reed contains only a single edge that chops the air flow in step-like fashion, and the single moving edge produces an unalterable pattern of pulses. Thus, the freedom to vary the musical timbre is restricted by the single edge design of the conventional reed.
The parent patent application, of which this is a continuation-in-part, concerns novel methods of construction for free reed instruments to allow modification of the pitch and/or timbre of the reed. Previously such modifications were not practical, in view of conventional free reed instrument construction. Such construction can present some difficulty in applying the techniques of the parent patent application. In particular, air leakage through an inactive reed and the use of leather flaps complicate implementation, particularly on small reeds. In addition, when direct contact to a reed is employed in accordance with the parent invention, any presence of a leather flap interferes with the implementation. Additionally, reed duplication required by conventional design also requires duplication of construction when implementing the direct contact methods of the parent invention.
Accordingly, it is an object of this invention to improve the performance and versatility of free reeds in musical instruments. Another object is to allow single reeds to operate with the same combination of pitch and timbre for both directions of air flow.
Another object of this invention is to eliminate the need for leather flaps and improve the timbre of the resulting tone. A further object is to provide a greater range of timbre than is achievable with the vibrations of conventional free reeds. Still another object is to facilitate methods of construction described in the parent invention.